Grow ma'o as bush, groundcover
By Heidi Bornhorst
Ma'o or Hawaiian cotton is a native Hawaiian plant. This means that it got here without the help of people. It also means that we don't see ma'o much in modern Hawai'i because of our introduced animals, plants and pests that eat it or crowd it out; because of land development, all-terrain vehicles and because of fire. All these forces threaten native Hawaiian ma'o.
One of the few places it grows in the wild today is at Ka 'Iwi, between Sandy Beach and Makapu'u. You know what also happens there: people scrambling their motorbikes and four-wheel-drive trucks. While this can be fun, people don't realize that they are running over and killing this unique Hawaiian plant. A lit cigarette butt casually flipped out the window also spells peril. Ma'o plants and all their seeds for the next generations will perish in a fire. Hawaiian plants cannot handle fire the way weeds and pests from other places can.
Ma'o is in the Malvaceae or hisbiscus family; its scientific name is Gossypium tomentosum. It has many native Hawaiian relatives, as well as others throughout the tropics and is closely related to true cotton, as well. The flower of the ma'o looks something like a giant 'ilima blossom, except that the color is more bold and vibrant and the flowers are much more durable than those of 'ilima. (I wear the flowers in my hair and people have asked me if they were fake: They look too perfect)
This plant is a shrub three to six feet tall and equally as wide. It has silvery-green leaves that are shaped like kukui or maple leaves, clear yellow flowers two to three inches in diameter, and seed capsules that have brown, fuzzy seeds with short cotton-like hairs. Ma'o is readily propagated from seeds. A 24-hour hot-water soak improves germination. Ma'o can also be grown from cuttings and air layers.
Ma'o is attractive if grown naturally or pruned and shaped in the landscape; it can also be used as a specimen shrub, large potted plant or a hedge. You can trim it low to be a ground cover, which is really striking with the silvery leaves and bright golden blossoms.
Ma'o does have some pest problems from chewing and sucking insects (use standard wettable powder insecticides) and nematodes. Nematodes can be restrained by using Clandosan, incorporated with fertilizer and other amendments at the time of planting. Clandosan is a natural byproduct of the shellfish industry. The chitin contained in it is food for beneficial organisms that eat nematode eggs. Lots of mulch and organic matter also slow down and repel nematodes.
A light hand with fertilizer, or no fertilizer at all is a good gardening practice with ma'o. Excess fertilizer, especially nitrogen, encourages luxuriant growth and invites pests. Good soil preparation with additions of cinder or coral, along with some organic matter (ma'o, like other natives, needs perfect drainage) is good for this plant.
Careful watering is also important. A ma'o in a pot will always need regular watering. A plant in the ground, well nurtured for the first six months to a year, can survive and look great with little water. The leaves will become more silvery and the flowers more abundant with less water, but each gardener needs to be observant and fine-tune the amount of water for the microclimate in their garden.
Although ma'o is not useful for making cloth, it has been used by plant breeders to improve the pest resistance of commercial cotton.
The Hawaiians made a green ('oma'oma'o) dye for kapa (bark cloth) from ma'o. The Hawaiians were the best kapa makers in all of Polynesia due partly to the abundant native plants and hardwoods for kapa beaters, anvils and abundant fresh water for soaking and preparing kapa.
Heidi Bornhorst is director of Honolulu's five botanical gardens. You can e-mail her at islandlife@honoluluadvertiser.com or write her c/o Island Life, Honolulu Advertiser, P.O. Box 3110, Honolulu, HI 96802.
